This protocol will assess whether HIV infected patients who have received more than one year of hard capsule saquinivir will have an acute decrease in plasma HIV RNA following substitution of this therapy with Indinvir (IDV) or the soft gelatin saquinivir. Other objectives are to assess the nature and duration of plasma RNA over 48 weeks; ascertain whether there are baseline mutations in the protease gene and the extent to which resistance develops; describe CD4 and CD8 changes and to determine safety and tolerablity of these drugs.